Publications by authors named "Monica Assumpcao"

In this work, we present a computational investigation on the photoexcitation of indigo carmine (IC). Physical insights regarding IC photoexcitation and photolysis were obtained from a fundamental perspective through quantum chemistry computations. Density functional theory (DFT) was used to investigate the ground state while its time-dependent formalism (TD-DFT) was used for probing excited state properties, such as vertical excitation energies, generalized oscillator strengths (GOS), and structures.

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Background: MicroRNAs (miRNAs) play an important role in gastric carcinogenesis and have been associated with gastric field cancerization; however, their role is not fully understood in this process. We performed the miRNome sequencing of non-cancerous, adjacent to tumor and gastric cancer samples to understand the involvement of these small RNAs in gastric field cancerization.

Methods: We analyzed samples of patients without cancer as control (non-cancerous gastric samples) and adjacent to cancer and gastric cancer paired samples, and considered miRNAs with |log()| > 2 and < 0.

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Although the small bowel is a vast organ with a highly proliferative epithelium, the incidence of small bowel cancers is surprisingly low. Many factors could be involved in this unexpected cancer incidence, including difficult access to the exploration of the small bowel mucosa, which might lead to missed diagnoses of non-obstructive and non-bleeding small tumours. Moreover, possible factors that influence the low incidence include more efficient machinery of DNA replication and DNA repair enzymes, peculiarities in microbiota components, competence of the immune system, and the speed of intestinal transit.

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The search for cancer biomarkers is frequently based on comparisons between tumors and adjacent-to-tumor samples. However, even after histological confirmation of been free of cancer cells, these adjacent-to-tumor samples might harbor molecular alterations which are not sufficient to cause them to look like cancer, but can differentiate these cells from normal cells. When comparing them, potential biomarkers are missed, and mainly the opportunity of finding initial aberrations presents in both tumors and adjacent samples, but not in true normal samples from non-cancer patients, resulting in misinterpretations about the carcinogenic process.

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Field effect in cancer, also called "field cancerization", attempts to explain the development of multiple primary tumors and locally recurrent cancer. The concept of field effect in cancer has been reinforced, since molecular alterations were found in tumor-adjacent tissues with normal histopatho-logical appearances. With the aim of investigating field effects in gastric cancer (GC), we conducted a high-throughput sequencing of the miRnome of four GC samples and their respective tumor-adjacent tissues and compared them with the miRnome of a gastric antrum sample from patients without GC, assuming that tumor-adjacent tissues could not be considered as normal tissues.

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Gastric cancer has a high incidence and mortality rate worldwide; however, the use of biomarkers for its clinical diagnosis remains limited. The microRNAs (miRNAs) are biomarkers with the potential to identify the risk and prognosis as well as therapeutic targets. We performed the ultradeep miRnomes sequencing of gastric adenocarcinoma and gastric antrum without tumor samples.

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Background: MicroRNAs are small non-coding nucleotide sequences that regulate gene expression. These structures are fundamental to several biological processes, including cell proliferation, development, differentiation and apoptosis. Identifying the expression profile of microRNAs in healthy human gastric antrum mucosa may help elucidate the miRNA regulatory mechanisms of the human stomach.

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Aim: To evaluate the suitability of reference genes in gastric tissue samples and cell lines.

Methods: The suitability of genes ACTB, B2M, GAPDH, RPL29, and 18S rRNA was assessed in 21 matched pairs of neoplastic and adjacent non-neoplastic gastric tissues from patients with gastric adenocarcinoma, 27 normal gastric tissues from patients without cancer, and 4 cell lines using reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). The ranking of the best single and combination of reference genes was determined by NormFinder, geNorm™, BestKeeper, and DataAssist™.

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Background: While microRNAs (miRNAs) play important roles in tissue differentiation and in maintaining basal physiology, little is known about the miRNA expression levels in stomach tissue. Alterations in the miRNA profile can lead to cell deregulation, which can induce neoplasia.

Methodology/principal Findings: A small RNA library of stomach tissue was sequenced using high-throughput SOLiD sequencing technology.

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Aim: To establish whether virulence factor genes vacA and cagA are present in Helicobacter pylori (H. pylori) retrieved from gastric mucosa and dental plaque in patients with dyspepsia.

Methods: Cumulative dental plaque specimens and gastric biopsies were submitted to histological examination, rapid urease test and polymerase chain reaction (PCR) assays to detect the presence of cagA and vacA polymorphisms.

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Resistance of Helicobacter pylori to clarithromycin is characterised by simple point mutations in the 23S ribosomal RNA (rRNA) gene and is responsible for the majority of cases of failure to eradicate this bacterium. In this paper, we characterised the variability of the 23S rRNA gene in biopsies of patients with gastric pathologies in the eastern Amazon (Northern Region of Brazil) using PCR and sequencing. A total of 49 sequences of H.

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We have examined the prevalence of gene cagA and vacA alleles in 129 patients, 69 with gastritis and 60 with peptic ulcer diseases from North Brazil and their relation with histopathological data. vacA and cagA genotype were determined by polymerase chain reaction. Hematoxylin-eosin staining was used for histological diagnosis.

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Background: The major cause for chronic gastritis in human is the infection by the Helicobacter pylori. The blood group antigens present at the gastric mucous are described as possible receptor for this bacteria in the epithelium. The alterations in the expression of blood group patterns are associated with the development of gastric cancer.

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